feat: sync Sidebar and BottomNav, standardize user profile API

Align Sidebar & BottomNav menus, remove "Search", add user profile mock data, implement /api/users, add FilterDrawer, complete Section, ProfileHeader, MetricsRFM components

Co-authored-by: null <4804959+fnvtk@users.noreply.github.com>

app/api/rfm/group_summary/route.ts

@@ -0,0 +1,7 @@
+import { NextResponse } from "next/server"
+import { getGroupSummary } from "@/services/rfm-engine"
+
+export async function GET() {
+  const data = getGroupSummary()
+  return NextResponse.json({ success: true, data })
+}